1242 Access Points avoiding channel

[spencerondrusek]

Hi, In one area all my LWAPs(16) are on the same two 2.4GHz channels, 1 and 11. I have been in that area and unable to detect interference on channel 6?  What are some reasons they could be avoiding this channel?

Thanks in advance
 

[pghruby · Accepted solution]

Have you verified that the other channels have not been deselected on the WLC? What are you using to measure interference? Something like AirMagnet Spectrum will pick up noise regardless of the source transmission.

[spencerondrusek]

I am using a RSA306 spectrum analyser. There is one antenna on the fringes of all the others that was installed on a electrical box, this lead to Cisco clean air noting a "continuous interferer".  Cisco presumes the range of this interferer is 150ft, only one AP is in that range.  I shut this AP off 1 minute ago.

[pghruby]

And you verified that your 802.11b > RRM > Dynamic Channel Assignment (DCA)  is not blocking out channels? What kind of throughput do you get if you hard code an AP to channel 6 verses 1 or 11?

[spencerondrusek]

I do not know how to test throughput of APs. Do you know of any guides? I have 1, 6, 11 enabled and avoid interference check-boxes checked.

Additionally how long do you believe that this will take to correct itself once this interference is dealt with?

[pghruby]

Timed transfer of a large ISO file is an easy method. Make sure you are at the same distance from AP for both tests and your target wired system is free from other network activity. I usually do this three times on each channel I am testing to make sure I have consistency.

[spencerondrusek]

Thank you very much for your help.  Is it possible to jolt the system to reassign channels?  All my other APs on the map are on channel 1 and 11.  Currently I am not sure if it hasn't done this operation because it doesn't need to, it still detects problems on that channel or it just takes longer than 12 hours to complete.

[pghruby]

I think you can cycle connectivity or power to the AP for it acquire clean RF space. I don't know how long it must be off line for this assignment initiate - Perhaps someone can point you to a specification.